Many disease causing microorganisms, such as bacteria, fungi, and viruses, play a significant role in producing a myriad of diseases and conditions in humans and animals. Due to their widespread capability of pathogenic infectivity, morbidity and mortality, considerable activity has been devoted towards developing convenient effective methods to help prevent or treat these diseases caused by these pathogens.
For example, viruses such as influenza, have a high mortality rate in humans and are devastating to man and animals. It is estimated that more than $1 billion per year is lost in productivity from absence due to sickness from an influenza virus infection.
With respect to clinical veterinary medicine, there are many diseases, viral and bacterial, that are detrimental to animals. Viruses or bacteria that cause diseases that effect animals in the food industry, for example, cattle, pigs and chickens can be quite costly and result in billions of dollars lost in the food industry. These same microorganisms can wipe out large masses of domestic animals, such as cats and dogs, since they can be highly contagious and spread quickly, thus being detrimental to veterinary hospitals, kennels, and breeding facilities, resulting in both emotional and monetary loss. Recently, there have been several disease causing microorganisms that have jumped the species barrier, resulting in new variant diseases that are fatal to man.
Canine parvovirus (CPV), for example, has a high morbidity and mortality rate and is a life threatening infection that has been estimate to affect up to 1 million dogs per year in the United States. The disease resulting from parvovirus is typically almost always fatal, and there have been very few major advances in the way that dogs with canine parvovirus are treated. As a result, the disease is typically associated with a significant mortality rate. Most of the untreated dogs succumb to the diseases, and even with care, for example, in private practice, mortality rate still is quite high. In addition, the disease from a parvovirus infection is costly, both monetarily and emotionally for the dog's caretakers.
With canine parvovirus, the clinical disease is often characterized by fever, acute gastroenteritis, which can progress rapidly to shock and death. Septicemia and endotoxemia can play an important role in the pathogenesis of canine parvovirus. It has been found that when gnotobiotic (germ free) dogs were infected with canine parvovirus, they did not develop any signs of the illness. Similar findings were made with germ-free cats when exposed with highly pathogenic feline parvovirus. Thus, attempts have been directed to utilize treatments aimed at preventing or treating septicemia and endotoxemia. Unfortunately, these treatments have shown little or no benefit on survival of these animals.
Conventional methods towards the control of these disease causing microorganisms or pathogens, include vaccination, drug therapy and public health measures. Typically, one method of treatment of these types of diseases is antibiotic therapy, which has been found to be effective against diseases caused by bacteria. Although an invaluable advance, there are disadvantages of using antibiotic therapy, especially when strains of bacteria appear to be resistant to antibiotics.
Vaccines have also been used to treat diseases caused by viruses. However, there can be disadvantages involved with the production of suitable vaccines. First, the vaccines derived from whole killed or whole attenuated viruses, may retain residual disease causing activity. Further, vaccines typically are reformulated each year in response to antigenic variation and are known to be ineffective against new viral variants.
Additional disadvantages are that medications typically can be expensive, especially if animals are on antibiotics, for example, over a long course of time, eventually often resulting in an agonizing imminent death of these animals.
As those skilled in the art would appreciate, there is a need for methods that can decrease the infectivity, morbidity and mortality associated with exposures to such pathogens. Such compositions and methods of treatment should preferably not have the undesirable properties of promoting microbial resistance, or being toxic to the recipient. Still further, there is a need for treatment and prevention in diseases caused by microorganisms that are cost effective and do not take a long period of time. In addition, there is a need to provide treatment of infectious diseases by developing biology based therapies.